Ignition device



1,641,421 Sept. 6, 1921 Q FRENCH IGNITION DEVICE Filed July 24, 1925 X9I I /7 /2 H I l7 /0 23' v INVENTOR 6w; Q FWGIL I) bl Patented Sept. 6,1927.

LOUIS 0. FRENCH, OF MILWAUKEE, WISCONSIN.

IGNITIODI DEVICE.

Application filed July 24, 1925. Serial No. 45,831.

The invention relates to ignition devices, and more particularly toigniters of the in candescent type.

lVhen liquid fuel issues from a spray nozzle, a relatively concentratedjet is formed along the axis of projection surrounded by a misty fringeof finely divided fuel particles, temporarily suspend-ed in the airaround the main jet. One of the objects of this invention is to takeadvantage of this condition and arrange the electrically-heatedincandescent element at the nozzle and outside of the main spray and inthe region of the fuel mist given off by the spray as it issues from thenozzle, with the result that the main spray is not impeded in its fiow;the ignition of the fuel mist is readily effected by the wire, and itsignition will in turn ignite the main stream, as the ignition of thismistoccurs at the start of injection and through its flame propagationacts to convert the main spray into a stream of flaming fuel. Such astream of burning fuel has decided advantages for starting purposes, orfor use as a pilot ignition for another fuel charge, because the warmingprocess is quickly effected, due to the heat furnished by the burningspray, and the fuel does not have a chance to coalesce or deposit itselfupon the cold. or cooler walls of the chamber into which it is beingsprayed, or upon other parts associated with the chamber.

As a further consequence of arranging thewire in the region of the mistand outside the main jet, I find that the heat necessary to ignite themist is less than that required where the main spray, or apart of it, isdirected against the wire, with the result that av relatively short wiremay be used, which has the advantage of reducing the amount of currentnecessary for ignition, and reducing the liability of the wire burningout quickly under high temperatures encountered in the engine, sincewith a short wire the relative rate of conductivity to the coolerterminals will serve to keepthe temperature of the wire from becomingexcessive.

This application is a continuation in part of an application forignition devices filed by me ,on March'25, 192, Serial No. 18,206. andan application for ignition devices filed by me on June 5, 1925, SerialNo. 35,119,

as to common claimable subject-matter. In these prior appllcations thefuel conduit was insulated from the main body of the casing,

element;

and while this had certain advantages, it had the disadvantage ofnecessitating a packed and insulated oint for the fuel supply pipe, or aconduit section of insulating material in the fuel line. I find that apacked and insulated joint in the fuel line complicates the constructionand increases its cost, and is liable to leakage, and I find that aconduit section of insulating material is liable to crack or ruptureunder the fuel pressures commonly used, and that it is difficult to makeand maintain tight pipe connections therewith. To overcome thesedifficulties, I provide an insulated terminal for one end of the hotwire, independent of the fuel conduit, and ground the other end of thewire in any suitable manner.

As in the aforementioned application, Serial No. 35,119, I provide a hotsurface member associated with the jet in the same manner as the hotwire, which will perform the functions of the hot wire after the enginehas become heated and the current to the wire is cut ofi. p

The invention further consists in the several features hereinafter setforth and more particularly defined byv claims at the conclusion hereof.

In the drawings: Fig. 1 is a vertical sectional view through an igniterembodying the invention, taken along the line 11 of Fig. 2; p

Fig. 2 is a bottom end View of the igniter shown in Fig. 1, with the hotsurface'elem-ent removed;

Fig. 3 is a side view. of the hot surface Fig. '4: is a verticalsectional view of a modified form of the device;

Fig. 5 is a detail view of an incandescent element before securing it tothe ignitor.

Referring to Figs. 1 moral 6 designates a plug casing having threadedengagement with the cooled engine cylinder or head 6, 7 a terminalmember, and 8 an exposed, ance element or wire. 7 I

The terminal member 7 is inthe form of a bolt which ismounted inbut'insulated from the casing 6 by a micasleeve 9 and a metal washer-'12which has a terminal exto 3, and 5, the nuelectrically-heatedresisttension 13; provided with a supply wire binding screw 14.

The head 7 of the bolt 7 has a transverse opening to receive one end ofthe element 8 which is clamped therein by a screw 15 in threadedengagement with the head and extending at right angles to and intocontact with the wire. The other end of the wire is grounded on andsecured to the casing 6 by a screw 16 in threaded engagement with thelower end of the casing from which heat is conducted to the cooled heador cylinder 6 of the engine.

A fuel injector is secured to or formed integral with the casing 6. Asshown, the injector is formed in the casing by a conduit 17 and a spraynozzle or discharge opening 18.

To control the supply of fuel to the engine, any suitable valve may beassociated with the spray nozzle, and in the present instance I haveshown a check valve fitting 19 secured to the casing and having a checkvalve 20 held closed by a spring 21 and opened by fuel pressure.

The incandescent element, connected, as above described, immediately infront of the nozzle 18, is in the form of a coil surrounding butdisposed outside of the main path of the fuel jet issuing from thenozzle 18 and in the region of the mist or outer fringe of the spray.With a wire of relatively heavy gauge, such as No. 16 B. d: S, a singleplain coil may be used but with wires of smaller gauge, such as 19 B. &8., or smaller, I find that better ignition is produced by forming thewire as shown in Fig. 5, that is, into a. looped or corrugated form withthe sides 22 of the corrugations or loops extending substantiallyparallel with the axis of the main jet. IVith such an arrangement thewire 8 does not interfere with the flow of the jet,

and the mist of finely divided fuel particles given off as the fuelissues from the nozzle and which are temporarily suspended in the airaround the jet are quickly ignited by the wire, and I find that thisignition takes place as soon as the fuel starts to flow from the nozzle18 and that the flame thus produced acts to ignite the main stream offuel as it flows from the nozzle, with the result that the spray isconverted into a stream of flaming fuel. This would not happen if thejet or heavy spatter from the jet were directed against the wire, as isthe general practice, because under such conditions the wire is cooledrapidly and ignition is retarded and when it does take place islocalized and by that time much of the spray has been deposited upon thecold or relatively cool walls of the engine. However, where the liquidfuel is converted into a flaming stream the warming process is quicklyeffected, due to the greater heat furnished, and the chance of the fuelcoalescing and depositing itself upon the cold or cooler walls of thechamber into which it is being sprayed are minimized.

In some engines the temperature conditions are not such as to causecontinued automatic ignition after the engine is started, but are such.as to furnish heat to a hot surface which will cause ignition, and Ihave associated a hot surface member 23 with the injector and hot wirein such a manner as to have said member assume the function of ignitingthe fuel after the current to the wire is cut off. In Figs. 1 and 3 thismember is shown in the form of a sleeve or tube having one end adaptedto fit over the reduced end 23 of the casing and having a body part 24heat-insulated from said end by a plurality of slots or holes 25 andwith its lower part 26 converging inwardly to a central opening 27alined with the axis of the fuel jet. The size of the opening 27 is suchthat its edges or the adjacent walls 26 are not et1mp1ng1ng surfaces butare disposed outside of the main path of the fuel 7 jet and in theregion of the mist or outer fringe of the spray, with the result that asthe lower end of said member becomes highly heated, during the runningof the engine, the mist of finely divided fuel particles temporarilysuspended in the air around the jet are ignited by this member and servejust as explained in connection with the wire to convert the spray intoa flaming stream so that ignition of the charge follows its injectioninto the engine, and, the main body of said member 23 is kept hot itsheat-insulating connection with the casing 4. r

In the form shown in Fig. 1 the fuel injector is shown as separate fromthe ignitor casing 29, which is here shown as a'conduit or couplinghaving a threaded connection 30 at one end, with the cooled cylinder orhead 30 of the engine and a threaded opening 31' at the other end totake the injector-plug or casing 32. This casing 32 has a. fuel conduit34 with a check valve fitting 35, similar to the check valve 19 shown indetail in Fig. 1, at one end, and a removable nozzle member 86 havingthe spray opening 37 therein. The incandescent element 38 is here shownin the form of a single coil arranged withreference to the opening 37 inthe same way as the element 8. One end of this coil is grounded to theshell 29 by aclamping screw 39, while the other end is mounted in thehead of a bolt 40 and secured'thercto by a screw 41. The bolt 40 extendsthrough an opening in the side wall of the casing 29 and is suitablyinsulated therefrom by mica washers 42 and a mica sleeve'43, and isclamped thereto in the same manner as the bolt 7 by a nut 44. A currentsupply wire binding nut 45 is mounted on the threaded end of said bolt.A hot surface member 46 in the form of a flanged ring has a tight fit inthe bore 47 of the casing 29 With a central opening 48 and slots 4:9 toheat-insulate the ring portion from its securing flange, the size of theopening 48 being related to the fuel nozzle 37 in the same Way as theopening 27 related to the nozzle 18.

In. either" case current from a battery or other suitable source ofsupply is conducted to the insulated terminal member or electrode andpasses through the Wire to the plug casing connected With the engineWhich has a ground circuit to the current source.

The ignitor With the resistance element alone may be used as a startingignition device for injection type internal combustion engines in Whichthe heat of compression is insufficient to start the engine from cold,the current to the Wire being cut off after the engine has become Warm,or it may be used as a pilot ignition device whereby the flaming sprayis used to ignite another charge of heavier fuel Where the engine Workson low or medium compression pressures, in Which case the current to theWire may be supplied intermittently. Furthermore, Where the compressionor heat developed in the engine is insufficient to continue subsequentignitions. under varying loads, during running, With the current to theWire shut off, I haveprovided a hot surface member to effect ignition.In both instances the main flow of the fuel jet into the combustionchamber of the engine is not interfered With and the Wire and hotsurface member are so disposed as to most readily effect the ignition ofthe fuel charge, and in the case of the Wire at relatively smallexpenditure of electrical energy and under conditions preventing rapiddeterioration of the Wire.

I desire it to be understood that this invention is not to be limited toany particular form or arrangement of parts except in so far as suchlimitations are included in of an exposed electrically-heated coiledignition Wire arranged adjacent the discharge nozzle of the ln ector andthrough Which the main spray has an unobstructed path as 1t issues fromsaid nozzle, said Wire being disposed in the region of the fuel mistgiven off by the fuel on its issuance from the nozzle.

3. The combination With a fuel injector, of an exposedelectrically-heated coiled ignition Wire arranged adjacent the dischargenozzle of the injector and through which the main spray passes directlyafter leaving the nozzle, said Wire being disposed in the region of thefuel mist given off by the fuel on its issuance from the nozzle andhaving looped portions extending substantially parallel With the axis ofthe nozzle.

4. The combination of a casing provided with a fuel conduit and spraynozzle, a fuel control valve associated With said conduit, an electrodedistinct from said nozzle and mounted in said casing and insulatedtherefrom, an electrically-heated resistance element disposed in theregion of the fuel mist given off by the fuel on its issuance from saidnozzle, arranged in close proximity to said nozzle and past Which themain spray has an unobstructed path as it issues from said nozzle, saidelement having one end secured to said electrode and the other endsecured to said casing.

5. The combination with a fuel injector, of an electrically-heatedresistance element arranged adjacent the discharge end of the injectorand outside of the main spray and in the region of the fuel mistsurrounding the main spray, and a hot surface ignition member past Whichthe main spray passes unobstructively and arranged at the discharge endof the injector and outside of the main spray and in the region of thefuel mist surrounding the spray.

6. The combination With a fuel injector having a casing, of'anelectrically-heated resistance element arranged adjacent the dischargeend of the injector, and a member secured to the casing and having aheat-insulated hot surface portion disposed adjacent the discharge endof the injector and spaced from the main path of the spray.

7. An ignition device for injection type internal combustion engines,comprising a casing having means connecting the fuel injector With thecombustion chamber of the engine, and an electrically-heated resistanceelement associated with said casing and arranged to ignite fuel mist asit formsat the discharge end of the injector about the main spray as thefuel charge issues from the injector. I

In testimony whereof, I affix my signature.

LOUIS O. FRENCH.

